How do you diagnose and treat pulmonary hypertension?

Diagnosis and Treatment of Pulmonary Hypertension

Right heart catheterization is mandatory for the definitive diagnosis of pulmonary hypertension, which is defined as a mean pulmonary arterial pressure >20 mmHg. 1, 2

Diagnostic Algorithm for Pulmonary Hypertension

Step 1: Initial Evaluation

• Clinical suspicion: Assess for symptoms including dyspnea, fatigue, chest pain, syncope, and signs of right heart failure 1
• First-line screening: Transthoracic echocardiography to estimate pulmonary arterial pressure and assess right ventricular function 1, 2
• Basic testing:
  • ECG (look for right ventricular hypertrophy, right axis deviation)
  • Chest radiograph (enlarged pulmonary arteries, right heart enlargement)
  • Pulmonary function tests with DLCO measurement
  • Arterial blood gases
  • Basic laboratory tests (complete blood count, biochemistry, immunology)
  • HIV testing
  • Thyroid function tests 1, 2

Step 2: Identify Common Causes

• Evaluate for left heart disease and lung diseases through:
  • Symptoms, signs, risk factors
  • ECG, pulmonary function tests, chest radiograph
  • High-resolution CT of the lungs 1

Step 3: Exclude Chronic Thromboembolic Pulmonary Hypertension

• Ventilation/perfusion lung scan: Mandatory in all patients with unexplained PH to exclude CTEPH 1, 2
• CT pulmonary angiography: Required if V/Q scan shows mismatched perfusion defects 1, 2

Step 4: Definitive Diagnosis

• Right heart catheterization: Essential for confirming diagnosis and hemodynamic classification 1, 2
  • Diagnostic criteria: mean pulmonary arterial pressure >20 mmHg
  • Additional parameters: pulmonary artery wedge pressure (PAWP), pulmonary vascular resistance (PVR)
  • Classification based on hemodynamics:
    • PAH: mPAP >20 mmHg, PAWP ≤15 mmHg, PVR >3 Wood units
    • PH due to left heart disease: mPAP >20 mmHg, PAWP >15 mmHg
    • Other classifications based on etiology 1

Step 5: Classification of PH

1. Pulmonary arterial hypertension (Group 1)
2. PH due to left heart disease (Group 2)
3. PH due to lung diseases (Group 3)
4. Chronic thromboembolic PH (Group 4)
5. PH with unclear/multifactorial mechanisms (Group 5) 3, 4

Treatment Approach

General Measures

• Avoid pregnancy in patients with PAH (Class I recommendation) 1
• Immunization against influenza and pneumococcal infection (Class I recommendation) 1
• Supervised exercise rehabilitation for deconditioned patients (Class IIa recommendation) 1
• Avoid excessive physical activity that causes distressing symptoms 1

Supportive Therapy

• Diuretic treatment for patients with right ventricular failure and fluid retention 1
• Continuous oxygen therapy when arterial blood O₂ pressure is consistently <60 mmHg 1
• Consider oral anticoagulation in idiopathic PAH, heritable PAH, and anorexigen-induced PAH 1

Specific PAH Therapy

Based on severity classification (low, intermediate, or high risk) 1:

1. Low risk patients (estimated 1-year mortality <5%):

   • WHO-FC I or II
   • 6MWD >440m
   • No signs of clinically relevant RV dysfunction

2. Intermediate risk patients (estimated 1-year mortality 5-10%):

   • Typically WHO-FC III
   • Moderately impaired exercise capacity
   • Signs of RV dysfunction but not failure

3. High risk patients (estimated 1-year mortality >10%):

   • WHO-FC III or IV
   • Progressive disease
   • Signs of severe RV dysfunction or failure 1

Pharmacological Treatment for PAH

• Initial therapy options:

  • Phosphodiesterase type 5 inhibitors (e.g., sildenafil) 5
  • Endothelin receptor antagonists
  • Prostacyclin analogues (e.g., epoprostenol) 6
  • Soluble guanylate cyclase stimulators

• Epoprostenol administration (for severe cases):

  • Administered by continuous intravenous infusion via central venous catheter
  • Initial dose: 2 ng/kg/min, increased in increments of 2 ng/kg/min every 15 minutes
  • Maintenance: Adjusted based on symptoms and tolerability 6

• Sildenafil administration:

  • Oral administration, typically three times daily
  • Contraindicated with nitrate medications due to risk of severe hypotension 5

Treatment of Other PH Groups

• CTEPH: Surgical pulmonary endarterectomy for eligible patients; riociguat for inoperable cases 3
• PH due to left heart disease: Focus on treating the underlying cardiac condition 3
• PH due to lung disease: Treat the underlying lung disease; oxygen therapy when indicated 3

Monitoring and Follow-up

• Regular assessment every 3-6 months in stable patients 1
• Evaluation should include:
  • Clinical assessment and WHO functional class
  • Exercise capacity (6-minute walk test)
  • Echocardiography
  • BNP/NT-proBNP levels
  • Right heart catheterization when indicated 1

Prognostic Factors

• WHO functional class
• Exercise capacity (6MWD)
• Right ventricular function
• Presence of pericardial effusion
• Hemodynamic parameters (RAP, cardiac index)
• BNP/NT-proBNP levels 1, 7

Early diagnosis and prompt referral to specialized centers are crucial for optimal management of pulmonary hypertension, particularly for PAH and CTEPH, which have specific approved therapies 2, 3.